Guidelines for breast cancer treatment.

Guidelines for breast cancer treatment.

Article by Assoc. Prof. Yaowanuch Kongdan, M.D.

Once diagnosed with breast cancer, treatment approaches vary depending on the stage and type of cancer. Staging the disease requires information from three sources:

• Size of the piece, measured from the largest piece.

• The spread of cancer to the lymph nodes.

• The spread of cancer to other organs.

Once the three initial pieces of information are obtained, the stage of cancer will be determined, ranging from stage 0 to 4. Treatment will depend on the stage of the disease as follows:

Stage zero breast cancer (0) is a cancer that has not spread outside the milk ducts. The chance of it spreading to the lymph nodes is only 1-2%. If treated correctly, the chance of a cure is over 98%. The main treatment for this stage of cancer is surgery, and other treatments are as follows:

1. Breast surgery: There are two methods: total mastectomy and breast-conserving surgery. If the breast-conserving method is chosen, radiation therapy to the cancerous breast is also required to achieve a treatment outcome similar to a total mastectomy. In cases where a total mastectomy is chosen, breast reconstruction can be performed at the same time.

2. Axillary lymph node dissection: Since stage 0 breast cancer has only a 1-2% chance of spreading to the lymph nodes, it is not necessary to remove all lymph nodes. Simply locating the sentinel lymph node, or the primary lymph node from which the cancer may have spread, is sufficient. This reduces the risk of arm swelling caused by unnecessary lymph node dissection.

3. Take anti-hormone medication to prevent and reduce the risk of breast cancer. Research has shown that Tamoxifen and Anastrozole can reduce the risk of breast cancer in high-risk women by up to 40%.

Early-stage breast cancer (Stages 1 and 2) is characterized by a tumor no larger than 5 cm, no lymph node metastasis (or no more than 3 lymph nodes), and no metastasis to other organs. The primary treatment at this stage is surgery, with other treatments being supplementary. Doctors use the stage and type of cancer to plan treatment. The type of cancer is determined through special tissue staining, including estrogen receptor (ER) and progesterone receptor (PgR) staining, the HER2 gene, and the Ki-67 value (indicating rapid or slow cell division). This information is then used to classify the cancer type, such as Luminal A, Luminal B, HER2, and Basal-like (Triple Negative).

The guidelines for treating early-stage cancer are as follows:

1. Surgery is divided into mastectomy and axillary lymph node dissection. Mastectomy has various methods, such as breast-conserving surgery, total mastectomy, or total mastectomy with nipple conservation and breast reconstruction. Axillary lymph node dissection should include sentinel lymph node dissection to locate the primary lymph node affected by cancer, reducing the risk of arm swelling after excessive lymph node dissection. In early-stage breast cancer, the chance of metastasis to the lymph nodes is less than 20%. Techniques for locating sentinel lymph nodes involve injecting isoflavones (iso-sulfan blue) and visually locating the lymphatic pathway to the primary lymph node. Some institutions may also use radiopharmaceuticals for increased accuracy. This technique involves injecting a radioactive substance and using instruments to detect the radioactive lymph nodes. Currently, newer technology uses injecting indocynine green and near-field infrared fluorescence imaging to visualize the lymphatic pathways and lymph nodes before surgery, resulting in highly accurate diagnosis, smaller incisions, and less extensive tissue dissection.

2. Chemotherapy is an adjuvant therapy indicated in cases where lymph node metastasis is found after surgery, and in cases where there is no lymph node metastasis but the tumor is 1 cm or larger in breast cancer, specifically Luminal B, HER2, and Basal-like (Triple Negative) types. The type is determined from estrogen receptor (ER) and progesterone receptor (PgR) staining, the HER2 gene, and Ki-67 levels. Chemotherapy as adjuvant therapy after surgery significantly reduces the risk of recurrence compared to surgery alone. The optimal timing for chemotherapy is approximately 4-8 weeks post-surgery. The chemotherapy regimen varies, but is typically given every 3 weeks for 4, 6, or 8 treatments.

3. Radiation therapy is an adjuvant treatment after surgery. It is indicated in all cases of breast-conserving surgery, or for tumors larger than 5 cm, or for cancer that has spread to the lymph nodes, or for cancer located close to normal tissue such as the posterior breast muscle. Radiation therapy should be started within 6 months of surgery and takes approximately 4-6 weeks. In addition to external radiation therapy, modern technology now offers intraoperative radiation therapy, which takes about 30 minutes. This is suitable for breast cancer patients who have undergone breast-conserving surgery, have tumors no larger than 3 cm, have estrogen receptor (ER), and are 45 years of age or older. Intraoperative radiation therapy is another option that makes it more convenient for patients.

4. Targeted Therapy: In patients with HER2-mediated cancer, adjuvant therapy should include targeted therapy targeting the HER2 receptor. This is administered as an injection every 3 weeks for 1 year. Currently, the standard treatment for single-site inhibition is Trastuzumab, suitable for patients without lymph node metastasis. However, for high-risk patients, such as those with lymph node metastasis, dual-site targeted therapy, using Trastuzumab in combination with Pertuzumab, can significantly improve treatment efficacy.

5. Hormone-Resistant Drugs: For cancers with estrogen receptor (ER) or progesterone receptor (PgR) systems, adjuvant treatment with hormone-reactive drugs is recommended. These include drugs such as tamoxifen, which can be used in both menstruating and postmenopausal women. Estrogen-inhibiting drugs, such as ovarian dysfunction in menstruating women, and aromatase inhibitors (ADIs) in postmenopausal women (e.g., letrozole, anastrozole, and exemestane), are also used. The most commonly prescribed hormone-reactive drug is tamoxifen, along with an aromatase inhibitor, taken once daily for 5 years. In high-risk cases, such as those with lymph node metastasis, the treatment duration may be extended to 10 years.

Locally invasive breast cancer (Stage 3) is treated similarly to early-stage breast cancer, except the initial treatment is usually not surgery. This is because the cancer is large or attached to vital organs, such as large lymph nodes near blood vessels or nerves. Surgery may not be able to remove all the cancer or may cause further injury to nearby organs. Therefore, chemotherapy (neoadjuvant chemotherapy) is given first to shrink the tumor before surgery is performed. Other treatments, such as radiation therapy, targeted therapy, and hormone therapy, are given as indicated, similar to early-stage breast cancer.

Metastatic breast cancer (stage 4) aims to manage symptoms, prolong disease remission, and extend patient life as much as possible. The primary treatment involves medication such as chemotherapy, HER2-targeted drugs, and anti-hormone therapy, depending on the type and nature of the cancer, the organs where it has metastasized, and the patient's physical and mental condition. Currently, several new drug classes are available, including targeted therapies (such as those inhibiting CDK4/6, MTOR, and PI3K) and immunotherapy. Surgery and radiation therapy are not necessary for this stage of cancer, and are only indicated in cases of scarring or pain. In addition to treating the cancer itself, complications arising from metastasis to other organs must also be managed. For example, bone metastasis can cause bone pain, fractures, or high calcium levels in the blood.

Note: Treatment results depend on the nature of the disease and the individual patient's condition. A guaranteed outcome cannot be guaranteed. Please consult a doctor for a personalized treatment plan.

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